1. Field of the Invention
The present invention relates to stator assemblies for motors, and more particularly to stator assemblies having improved magnetic conduction effect, thereby avoiding dead corner of rotation and increasing the rotating torque.
2. Description of the Related Art
FIGS. 11 and 12 of the drawings illustrate a conventional stator comprising an axle tube 91 having an upper pole plate 92, a bobbin 93, and a lower pole plate 94 mounted therearound. Walls 95 project outward from a portion of a periphery of the upper pole plate 92 and extend along a direction parallel to a longitudinal direction of the upper pole plate 92. Similarly, walls 96 project outward from a portion of a periphery of the lower pole plate 94 and extend along a longitudinal direction of the lower pole plate 94. Thus, the walls 95 and 96 provide a larger magnetically conductive area with a permanent ring magnet on a rotor. However, the sectional thickness of each of the upper and lower pole plates 92 and 94 is not increased although the induction area is increased, as the upper pole plate 92 and the lower pole plate 94 are formed by means bending silicon steel sheets of identical thickness. As a result, the magnetic conduction effect is poor, the rotational torque is insufficient, the rotation is unstable, and floating rotation may occur.
It is the primary object of the present invention to provide a stator assembly that has improved magnetic conduction effect to thereby increase the rotational torque.
It is another object of the present invention to provide a stator assembly without dead corner of rotation, thereby allowing easy starting of the rotor.
A stator assembly in accordance with the present invention comprises upper and lower pole plates or silicon steel sheets each having a plurality of radial poles. Each radial pole includes a magnetic pole face extending along a direction parallel to a longitudinal direction. The magnetic pole faces of each upper pole plate, each lower pole plate, or each silicon steel sheet may be of the same or different length. Alternatively, the magnetic pole faces may be overlapped with each other or not overlapped with each other. The overall magnetic pole face formed by the magnetic pole faces may be so arranged to represent a step-like structure or an inclined side.
Other objects, specific advantages, and novel features of the invention will become more apparent from the following detailed description and preferable embodiments when taken in conjunction with the accompanying drawings.